A great thing about wikis is that they can be searched. Try using the search box in the left hand pane. The default is to search the wiki you are in but you can also search other wikispaces. Try in your own area of interest.
Wikispaces is giving away 100,000 free wikis to R~12 educators. This is a great service as it enables you to set up open, protected or private wikis for education activities. Their usual price for ability to go private, and more importantly ad free, is USD $5 per month. Note: will need to get wikispaces unblocked at most school sites. Wiki Spaces is at http://www.wikispaces.com/site/for/teachers100Khttp:www.wikispaces.com/site/for/teachers100Khttp:www.wikispaces.com/site/for/teachers100K
An example of a photography course (still under development)
Two other spaces I have been playing with
Cegsa-conference-2006
http://theballen.wikispaces.com/